Conversion of liquid carbonaceous materials of high boiling point range



M. PIERv June 30, 1936.

CONVERSION oF LIQUID QARBoNAcE'oUs MATERIALS k0F HIGH BOILI'NG POINT'RANGEl Filed July 8, 1929 Patented June 30, 1936 CONVERSION OF ,LIQUID' CARBONACEOUS MATERIALS 0F HIGH BOILING POINT RANGE Mathias Pier, Heidelberg, Germany, assignor, by

mesne assignments, to Standard-I. G. Company, Linden, N. J., a corporation of Delaware Application July 8, 1929, Serial No. 376,861

`In Germany July 13, 1928 3 claims. (c1. 19a-5s) This invention relates to improvements in the conversion of liquid carbonaceous-materials of high boiling point range, for example hydrocarbons, into valuable products, especially hydrocarbons, mainly boiling at low temperatures, but also, if desired, those of comparatively high boiling point range having the character of lubrieating or transformer oils.

A process has already been proposed for the conversion of hydrocarbonsof high boiling point range, such as mineral oils, -tars and the like into valuable hydrocarbons, especially those boiling at low temperatures, according to. which theV initial materials are rst subjected to a continuous process of cracking with or without the employment of hydrogen under such conditions that carbonaceous deposits are formed with va minimum production of gas, the resulting'products, in conjunction with the said carbonaceous deposits, being then treated in a second stage at an elevated temperature and under pressure with hydrogen or gases supplying hydrogen, preferably in the liquid phase and in the presence or absence of catalysts. l

I have now found that higher throughputs may be obtained by subjecting the said initial materials in the first stage to crackingunder mild conditions, thereby foregoing ,a far-reaching formation of benzine, and also, if desired, without the occurrence of the formation of carbonionla, oxides of carbon and-the like, and is preferably carried out in a continuous manner. The most suitable temperature for the said mild cracking treatment will depend on the rate of throughput of the .initial materials, the pressure, and the nature of the extraneous gases employed. As a general rule, the temperature may be higher,.the higher the rate of throughput and the lower the pressure. As a rule temperatures of between about 450 and 650 centigrade will be particularly suitable for the cracking process,

Ia high lrate of throughput, for example, one cubic metre of treated material per, cubic metre of cracking space in one hour being employed. Atmospheric pressure is very advantageous for the process, but in some cases somewhat reduced or also elevated pressure may be employed. When hydrogen or a gas supplying hydrogen is employed as the extraneous gas, the pressure will be such that no substantial destructive hydrogenation of the initial materials takes place, and as a rule below about 10 atmospheres. If the` conditions are otherwise suitable for 'destructive hydrogenation the hydrogen is not employed in a quantity sufficient to eiect destructive hydrogeneration. When the cracking stage is carried out under pressure, it will often be advantageous ,not to release the pressure prior to destructive hydrogenation. As a rule it is advantageous to construct the cracking plant of materials, which do n'ot give rise to the formation of crusts of carbon, such for example as alloy steels or other refractory alloys. Where this point is a secondary consideration, iron may, however, also be employed.

During the cracking the liquid material may be led out from, and back into,the heating chamber without appreciable cooling. In this manner a good stirring is eiected and the deposition of coke or thick masses and th'e like is prevented.

For example the process may be carried out in such a manner that in the first stage only from 20v to 30 per cent lof the initial material are converted into benzine. 'I'he residues which remain. after. distilling oi the benzine are then treated in a destructive hydrogenation apparatus, preferably in the presence of a. catalyst immune from poisoning by sulphur withhydrogen under pressure, for example, pressures ranging from 50 up to 200 atmospheres or more, for example, of 300 to 1000 atmospheres or even more may be used, and at a temperature between 300 and 700 C. in order to obtain in particular hydrocarbons of low boiling point range. Thus for example from a combined cracking and destructive hydrogenationV apparatus it is possible by the process in' accordance with the present invention to draw oi only products of the nature of. benzines and to' convert the material completely into benzine by alternate treatment in the two partsof the apparatus. By the destructive. hydrogenation, those products which are no longer suitable for cracking are again rendered suitable for cracking.

The yields of benzine areconsiderably higher,

than whenthe products are cracked for a second time without the intermediate destructive hydrogenation.

From the Aresidues from the cracking which are unsuitable for the direct production of lubricating oils,- lubricating oils maybe obtained, forexample by subjecting the said residues to destructive hydrogenation, and isolating fractions suitable for employment as lubricating oils. This latter destructive 'hydrogenation is preferably carried out at very high pressures, for example, at pressures exceeding `100 atmospheres, such as 200, 300, 500, 1000 or 3000 atmospheres or even more.

In some cases it is preferable to separate the solid parailins from materials having a large content of solid paraiiins beforethe cracking. This may be eiected by cooling to low temperatures, or by the' employment of the known solvents or precipitating agents.

The destructive hydrogenation mayalso be carried out in several stages, diierent conditions of pressure or temperature or both being employed in each stage.

The cracking or the destructive hydrogenation or both stages of the process may be carried out in the presence of catalysts. Examples of these are catalysts comprising compounds containing sulphur in combination, for example metallic sulphides, in particular the heavy metal sulphides and more especially those of the iron group, either alone or as mixtures with one another -or with metals, metalloids, active charcoal, coke or the like or with oxides, hydroxides, or carbonates, or with other materials of a catalytic or of inert nature. lThe sulphur may also be combined with the catalyst by adding sulphites or sulphates thereto or by the addition of sulphur to metals or oxides. A very suitable lcatalyst may be obtained by treating iron with hydrogen sulphide at an elevated temperature. Particularly suitable catalysts of this class are for example cobalt sulphide, iron sulphide, zinc sulphide, nickel sulphide, manganese sulphide, molybdenum sulphide and the like or mixtures thereof, for example, mixtures of cobalt sulphide with nickel sulphide, or of cobalt sulphide with manganese sulphide, or of cobalt sulphide mixed with iron sulphide, or with zinc sulphide or with aluminium sulphide, with or without an addition of inert substances. Catalysts consisting of or containing molybdenum, chromium, tungsten, uranium or the compounds thereof or mixtures of those substances are also particularly suitable. As examples of this type of catalyst may bef-mentioned molybdic acid or ammonium molybdate, tungsten sulphide, tungstic acid, chromium hydroxide and chromic acid. Mixtures of chromium or tungsten with other catalysts such as with cobalt, nickel or iron may also be employed.l Activation of the catalysts or the additionv of substances increasing their mechanical strength may also be of advantage, this being effected for example with substances having a basic action such as potassium carbonate, aluminium hydroxide o r calcium carbonate. Carriers such 'as lumps of aluminium silicate may also be employed with advantage. As further catalysts maybe mentioned oxidic catalysts comprising zinc oxide, chromium oxide or manganese oxide or mixtures of these, if desired, with an .addition of a compound containing fixed nitrogen such as ammonium sulphide `or nitrides which are comparatively stable against the action of water, for example silicon nitride or titanium nitride.- These said oxidic catalysts may be employed in conjunction, with other substances such as lumps of nre-clay, quartz, asbestos, pumice, coke, active charcoal, metals, in particular heavy metals, metalloids, oxides, sulphides, carbides, and the like and mixtures thereof with the said substances. As still further examples of suitable catalysts may be mentioned those containing at least one of the elements silver, copper, cadmium, lead, bismuth, tin in the form of its compounds, further 'She difficultly reducible metal oxides or carbonates, such as magnesia, lithium carbonate, boric acid, alumina, the rare earths, including the diiiicultly reducible oxides of metals from the 4th group of the periodic system, or the oxides of zinc, manganese or vanadium. The catalysts may contain several of these substances or also other substances, for example metals from the 8th group of the periodic system, such as iron. As speciiic examples of these catalysts may be mentioned those obtained by impregnating porous refractory materials with a solution .of lead nitrate, or of stannous chloride, silver nitrate or of copper hydroxide, either alone orin admixture with compounds of iron, cobalt and the like. Further may be mentioned catalysts containing the oxides of silver or of titanium, or lithium carbonate, magnesite manganous oxide, silver borate or mixtures of copper oxide with cerous oxide or of silver with cobalt oxide and the like and also porous refractory masses coated with vanadium oxide or thorium oxide or with a mixture of compounds of i uranium and zinc or of silver and tungsten. These latter compounds may also be employed as such without applicationto the said porous materials. As further suitable catalysts may be mentioned catalysts containing active charcoal or the metalloids boron,l silicon, phosphorus, arsenic, selenium, tellurium or the compounds thereof or halogens. These metalloids may advantageously be employed together with elements from the 2nd to the 8th groups of the periodic system, in par- 1 ticular those selected from the 6th group of the periodic system. The catalysts may for example contain the following acids or their salts, namely phosphoric acid, arsenious acid, silicic acid, boric I acid, hydrofluoric acid, hydrochloric acid, selenious acidand the like. As specic examples may be mentioned silicon carbide, alderwood charcoal which has been glowed at 800 centigrade and impregnated with phosphoric acid, calcium phosphate, molybdenum phosphate, tungsten phos phate, iron phosphate, aluminium phosphate, arsenious acid together with molybdenum or tungsten, silicides, for example iron silicide containing 15 per cent of silicon, active silica,'hydrosi1icates, borides such as titanium boride or iron boride, calcium fluoride, molybdenum with l0 per cent of aluminium chloride, molybdenum with 10 per cent of cadmium chloride, molybdic acid with sodium selenite. Compounds containing fixed,l nitrogen may also be employed with advantage in the reaction. Thus ammonia or its salts, for example, ammonium sulphide and in some cases organic compounds of nitrogen may also be advantageous. Nitrides which are fairly stable against the action of water havebeen found to give par- C system or copper or gold or the compounds therefrom the 2nd to the 7th groups of the periodic y y ia,o4s,vc4

of. The elements'from the 2nd and 3rd groups may, however, also be employed in large amounts. Thus mixtures containing molecular proportions of molybdic acid with magnesia or with copper or with aluminium hydroxide, or mixtures of tungstic acid with zinc oxide or of vanadium oxide with magnesia furnish good results. Excellent catalysts' are further molybdic acid,with about 10 per cent of chromium oxide or of vanadium oxide,

molybdic acid with about 1 0 per cent of uranium from the system through valve oxide or of thorium oxide or of manganous mide,

cent of chromium oxide orof a mixture of uranium oxide, cobalt and a small amount of chromium oxide. .Again another very suitable class of catalysts is formed by the noble metals or lead or tin or compounds thereof on carriers, in particular on magnesia or magnesite or chromium oxide. As examples of this class of catalysts may be mentioned ruthenium, palladium, platinum, gold, lead or tin on magnesia or magnesite or platinum or gold on chromium oxide. Catalysts containing small amounts of silver or -of mixtures of copper with zinc or with cadmium in a free state or in chemical combination'and preferably also boron, or aluminium, or silicon, or titanium, or vanadium, or tantallium, or chromium,

` benzine are obtained. Moreover, the preli or molybdenum, or tungsten, or cobalt in fa free or combined state or mixtures of these are also very suitable. Examples of such catalysts are tantallic acid containing l per cent of silver, molybdic acid containing per cent of silver or silica containing l0 per cent of a mixture of copper and zinc. Again another class of catalysts consists of refractory metals or, alloys on which small amounts of solid oxides of elements having a vcatalytic action from the 3rd to the 7th groups of the periodic system have been deposited. The said metals or their alloys are preferably employed in an etched condition and preferably acidied solutions of salts of the said oxides are employed as the etching agents. i

The cracking and destructive hydrogenation in themanner hereinbefore described have the advantage that with large throughputs, if desired, without the deposition of carbon, high yields of minal'y cracking treatment under mild conditions has the advantage that the properties of the initial ma- The accompanying drawing diagrammatically shows an elevation partly in section of a plantv which is particularly suitable for carrying out the process according to the 'present invention.

" Referring to this drawing in detail heavy oil to be converted is introduced at I and pressed'by compressor 2 into the ipreheater 3. From this preheater the oil passes into cracking tubes 4d which are heated in vessell 5. In the said cracking tubes the oil is subjected to cracking under mild conditions as set forth above. The cracked o'il is then led into condenser 6 where the vapors of the hydrocarbons rheavier than benzines Iare condensed and discharged into stripping vessel 'i Vfrom which the uncondensed portion of the prodtaining the condensate is drawn' off at 9, passed by way of valve I0 through preheatenl I into vessel I2 where it is subjected to destructive hydrogenation. The hydrogenated Vproducts leave the vessel I2 at I3 and passby way of valve I8 into condenser Il where the constitutents not gaseous at ordinary temperatures are condensed. The fixed gases are separated from the product in stripping vessel I5 and may be either withdrawn I9 or recycled to the destructive hydrogenation chamber by way of pump 20. The liquid portion containing the condensate from stripping vessel V I5 is passed by way of valve I6 through pipe line 22 intothe rectifying column 23. Benzine is taken off overhead through line 24 and condensed in condenser 25. The remainder of the product is drawn off through line 26 and recycled to'line I from which it is introduced again into cracking tubes 4.

The following example willv further illustrate how this invention may be carried out in practice, but the invention is not'restricted thereto.y

Example y Mid-continent gas oil of which about 40 per cent bbils between 190 and 260,centigrade, 65 per cent boils up to 300 centigrade and about 90fper cen*l up to 400 centigrade, is continuously injected into a cracking apparatus and is cracked under a pressure of about 5 atmospheres and at a temperature of about 460 centigrade with a high throughput, for example one cubic metre of treated material per cubic meter of cracking space. The whole of the product without'releasing the pressure, is led into a rectifying column in which. the benzine and the products of higher boiling point are separated one from another. The benzine which is distilled off is withdrawn into a receiver which is under pressure. About from f.to per cent of benzine, calculated with reference to the injected gas oil, are obtained.

The residual higher boiling products of the `cracking pass from the rectifying column, While still hot, into a container and are led from thence, if desired after the separation of any carbona-I ceous deposits formed, into a high pressure reaction chamber in which they are subjected to a treatment with hydrogen under a pressure of about 200 atmospheres and ata temperature Aof about 450 centigrade in the presence of a catalyst prepared from molybdenum oxide and zinc oxide. By cooling at the rear of the reaction chamber, if necessary with the employment of a rectifying column, a product is obtained which is desulphurized to a great extent and which contains lfrom to 60 per cent of benzine. The remainder consists of a light gas oil which is suitable for working up into illuminating oil. is very rich in hydrogen it may be led backv for a further cracking for the purpose of complete conversion into benzine without y the occurrence of `the objections, for example'impairing of the yield Since this product 6 of benzine, which are noticeable when the middle 6'5 .oil arising from the cracking apparatus is directly led back againto the cracking process.

What I claim iszl. A process for the production of low boiling I liquid hydrocarbons rich in aromatic constituents uct is Withdrawn at 3. The liquid portion con-` cracking at a temperature between 450fand 650 75 said materials are'placed in a condition in which they are more amenable to destructive hydrogenation, separating from the total resulting cracked product any benzine formed, subjecting all the remainder of the total cracked product prior to recirculation of any portion thereof tothe erackin'g zone, to destructive hydrogenation at a temperature and pressure on the order of those usually employed for destructive hydrogenation to thereby place the heavier constituents of said remainder in a condition in which they can be further cracked to low boiling hydrocarbons, separating from the product of destructive hydrogenation any benzine formed and directly subjecting the remainder of the destructive hydrogenation product to a further cracking to produce low boiling hydrocarbons rich in aromatics, whereby the initial material is substantially completely converted into benzine by alternate subjection to said two types of conversion.

2. A process according to the preceding claim in which in the first stage the rate of throughput is such that from 20 to 30% of the initial material is converted into benzine and the conditions in the second stage are such that the product of the first stage is converted into a product containing about 50 or 60% of benzine, the remainder consisting of light gas oil rich in hydrogen.

3. -A process according to claim 1 in which the,

destructive hydrogenation is conducted under a pressure of about 200 atmospheres in the presence of a. catalyst containing the oxides of molybdenum and zinc. K

MATHIAS PIER. 

